Planar Drop-Sizing in Dense Fuel Sprays Using Advanced Laser Diagnostic Techniques

A reliable measurement of drop sizes and liquid fuel distribution in a spray is essential for best combustion efficiency and exhaust emission from I.C. engines. The droplet size and fuel distribution control air-fuel mixture formation and, hence, combustion characteristics. The chapter gives a concise summary of recent advances and developments in the LSD technique as a planar drop-sizing technique. The LSD technique relies on the principle that a ratio of planar laser-induced fluorescence (PLIF) and Mie signals is proportional to Sauter mean diameter (SMD). PLIF signal can also be used to determine the distribution of liquid in a spray. This makes LSD an attractive technique in dense spray characterization that can also provide liquid volume fraction distributions. A brief review of laser-based drop-sizing methods and working principle of LSD measurements are first discussed. Different approaches and limitations of the LSD technique are also summarized. Further, sources of error and ways to compensate these errors are explained in detail. Previous studies on LSD measurements in different fuel sprays of stationary combustion devices and I.C. engines are summarized. Finally, improvements in the LSD techniques are suggested, including structured laser illumination planar imaging (SLIPI) measurements, for reliable measurements in dense sprays

On Fair and Efficient Allocations of Indivisible Public Goods

We study fair allocation of indivisible public goods subject to cardinality (budget) constraints. In this model, we have n agents and m available public goods, and we want to select k ? m goods in a fair and efficient manner. We first establish fundamental connections between the models of private goods, public goods, and public decision making by presenting polynomial-time reductions for the popular solution concepts of maximum Nash welfare (MNW) and leximin. These mechanisms are known to provide remarkable fairness and efficiency guarantees in private goods and public decision making settings. We show that they retain these desirable properties even in the public goods case. We prove that MNW allocations provide fairness guarantees of Proportionality up to one good (Prop1), 1/n approximation to Round Robin Share (RRS), and the efficiency guarantee of Pareto Optimality (PO). Further, we show that the problems of finding MNW or leximin-optimal allocations are NP-hard, even in the case of constantly many agents, or binary valuations. This is in sharp contrast to the private goods setting that admits polynomial-time algorithms under binary valuations. We also design pseudo-polynomial time algorithms for computing an exact MNW or leximin-optimal allocation for the cases of (i) constantly many agents, and (ii) constantly many goods with additive valuations. We also present an O(n)-factor approximation algorithm for MNW which also satisfies RRS, Prop1, and 1/2-Prop

Dual Column, Replica Bitline Delay Technique Using Stochastic Current Processing for a Process Variation Tolerant, Low Power SRAM

SRAM (Static Random Access Memory) design has become the critical and important block in processing ICs with the highest bandwidth power rationed memories taking the business lead. As industry attempts to maintain Moore's law by shrinking the device size, we are facing greater issues with the variability due to random doping fluctuation in devices. This variation compels engineers to design for worst case conditions which leads to inefficient memory model, which make it difficult to stand in the business race. However, a smart design can lead to less variation and “exact” memory parametric prediction to achieve high performance, low power and maximum yield designs. Since, random variation today is more dominant, we consider the application of the central limit theorem to control memory read timing across PVT (Process Voltage Temperature) corners. A statistical read timing is developed for a SRAM memory bank. In the thesis two dummy columns, each at extreme end of the memory bank, are used to implement the statistical memory bank model. By combining Monte-Carlo analysis using cadence virtuoso, and PDK data for the CMOS process (IBM 7RF), an analytically memory timing model is verified. Our major goal is to improve yield across all memory banks in all die across all the wafers; slow-slow (SS), typical-typical (TT) and fast-fast (FF).A smart stochastic/statistical approach is used in the thesis to predict exact parametric yield parameters with less variation to design accurate memory system which gives high performance, low power and maximum yield across all PVT corners to keep you ahead in the memory business. The memory design is compared to the conventional self-timed replica architecture using coefficient of variance of a reference current generated using dummy column. The proposed architecture was able to achieve 62 percent across the process improved accuracy in reference current and sense amplifier firing variation. Proposed architecture looks promising for future node technologies where statistical variability and its impact in subthreshold region is more dominant.Electrical Engineerin

A rare case of ovarian thecoma in a postmenopausal woman

Thecomas are very rare solid tumors of ovary and are a type of sex-cord stromal tumors. They account for approximately 0.5%-1% of primary ovarian tumors. We report a rare incidence of this tumor which presented in a postmenopausal woman. She presented with abdominal discomfort and underwent an ultrasonography revealing a solid ovarian tumor. She underwent a total abdominal hysterectomy with bilateral salpingo-oophorectomy. Histopathological examination showed benign thecoma. Hence it is important to keep this benign condition in mind when dealing with solid ovarian tumors in postmenopausal woman

Cohort profile: Andhra Pradesh Children and Parents Study (APCAPS).

The Andhra Pradesh Children and Parents Study (APCAPS) was originally established to study the long-term effects of early-life undernutrition on risk of cardiovascular disease. Its aims were subsequently expanded to include trans-generational influences of other environmental and genetic factors on chronic diseases in rural India. It builds on the Hyderabad Nutrition Trial (HNT) conducted in 1987-90 to compare the effects on birthweight of a protein-calorie supplement for pregnant women and children. The index children of HNT and their mothers were retraced and examined in 2003-05, and the children re-examined as young adults aged 18-21 years in 2009-10. The cohort was expanded to include both parents and siblings of the index children in a recently completed follow-up conducted in 2010-12 (N=∼6225 out of 10,213 participants). Recruitment of the remaining residents of these 29 villages (N=∼55,000) in Ranga Reddy district of Andhra Pradesh is now under way. Extensive data on socio-demographic, lifestyle, medical, anthropometric, physiological, vascular and body composition measures, DNA, stored plasma, and assays of lipids and inflammatory markers on APCAPS participants are available. Details of how to access these data are available from the corresponding author

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Strukturvorhersage von Lithium, Calciumcarbid und (Per)nitridverbindungen bei Umgebungs- und Hochdruck auf Ab-Initio-Ebene

In recent years, new theoretical methodologies and techniques have become available to explore the energy landscape of chemical systems. Furthermore, experimental solid state chemistry has opened new opportunities by advances in controlling synthesis routes, for example by low temperature atom beam deposition. The present thesis deals with theoretical structure prediction of an elemental system, lithium metal, and binary systems such as calcium carbide and (per)nitride compounds using different ab-initio methods. Although lithium is a simple metallic system, various modifications are known, in particular both at low temperature and at high pressure. To gain further insight into the possible metastable or thermodynamically stable modifications of lithium at standard conditions, a global exploration of the energy landscape was performed. For the global optimization, we used simulated annealing, to identify possible structure candidates. A local optimization followed the global search, where the structure candidates were refined. We have found structures with space group Im-3m (bcc), Fm-3m (fcc), and P63/mmc (hcp). Apart from these known modifications, we have predicted one interesting new structure with space group Pm-3n, which shows chains of lithium atoms. This newly predicted structure corresponds to the A15 structure type. To understand the thermodynamic stability of this new polymorph, energy-vs-volume curves and enthalpy-vs-pressure curves were calculated and analyzed, and in order to estimate the dynamical stability, phonon calculations were performed. In the past, both ionic and covalent systems had been studied with simulated annealing using ab-initio energy calculations in all the steps. In this thesis, we considered CaC2 as an example of a mixed covalent-ionic system. Experimentally, four different modifications had been known. From the global optimization runs at standard pressure, we obtained 10 different structure candidates for this system. Among these, three exhibited a particularly low energy. One of them is the experimentally found (CaC2-I) structure, and a second one (CaC2-VI) has some similarity to the observed structure (CaC2-III). The last one is completely new (CaC2-V), and is lowest in energy of all the structures considered. Furthermore, at high pressure, CaC2 is predicted to stabilize in a new structure type (CaC2-VII), analogous to the CsCl-structure. Very recently, this high pressure modification was observed in high pressure experiments on the BaC2 system. The successful structure prediction for the CaC2 system suggested that binary pernitride compounds could also be a highly interesting class of systems with complex multi-minima energy landscapes. In this thesis, we considered pernitrides MN2, where M denotes cations with different maximal valences: II (Ca, Sr, Ba), III (La), and IV (Ti), some of which have not yet been synthesized (LaN2 and TiN2). Experimentally, CaN2 and SrN2 crystallize into a tetragonal modification (CaC2-I). BaN2 stabilizes into the ThC2 structure type. Here, we performed the prediction of new crystal structures with two methods: the global search as described before, and a simple database approach. In the latter approach, we considered the well-known AB2 structure types known from databases such as the Inorganic Crystal Structure Database (ICSD), replaced the anions and cations with N2 units and metal atoms, respectively, and performed a local optimization. We found the CaC2-I, ThC2, MgC2, and CaC2-V modifications among all pernitride systems as candidates for the stable modifications. In the case of CaN2, the CaC2-I and MgC2 structure types are stable modifications at standard and negative pressure, respectively. TiN2-I and CaC2-V are possible modifications for the TiN2 system at normal and high pressure, respectively. In the case of CaN2 and SrN2, N2 units are surrounded by octahedrally coordinated cations, whereas a distorted octahedron is formed by the cations in BaN2 and LaN2 at ambient conditions. Only for the TiN2 system, the N2 dumbbells are surrounded by Ti in a square pyramid. All these pernitride modifications are metallic in nature except TiN2-I. Pernitride systems have a negative binding energy with respect to the metal and elemental N2, which suggests that these systems might be synthesized e.g. at high pressure.Im Laufe der letzten Jahre sind neue theoretische Methoden und Techniken zur Erkundung der Energielandschaft chemischer Systeme verfügbar geworden. Daneben haben sich im Bereich der experimentellen Festkörperchemie neue Möglichkeiten durch Fortschritte in der Kontrolle von Syntheserouten ergeben, wie z.B. durch das Tieftemperaturatomabscheidungverfahren. Die vorliegende Doktorarbeit beschäftigt sich mit der theoretischen Strukturvorhersage eines Elements, metallisches Lithium, sowie binärer Systeme, wie Calciumcarbid und (Per)nitridverbindungen, unter Verwendung von verschiedenen ab initio Verfahren. Obwohl Lithium ein einfaches metallischen Systems ist, sind verschiedene Modifikationen bekannt, insbesondere bei niedriger Temperatur und unter hohem Druck. Um weitere Einblicke in mögliche metastabile oder thermodynamisch stabile Modifikationen von Lithium bei Standardbedingungen zu gewinnen, wurde eine globale Untersuchung der Energielandschaft durchgeführt. Für die globale Optimierung verwendeten wir Simulated Annealing, um mögliche Strukturkandidaten zu dentifizieren. Der globalen Suche folgte eine lokale Optimierung, bei der die Strukturkandidaten verfeinert wurden. Wir haben Strukturen mit den Raumgruppen Im¯3m (bcc), Fm¯3m(fcc), und P63/mmc (hcp) gefunden. Abgesehen von diesen bekannten Modifikationen, haben wir eine interessante neue Struktur mit der Raumgruppe Pm¯3n vorhergesagt, die Ketten der Lithium-Atome zeigt. Diese neu vorhergesagte Struktur entspricht dem A15 Struktur-Typ. Um die thermodynamische Stabilität dieses neuen Polymorphs zu verstehen, wurden Energie und Enthalpie als Funktion vom Druck berechnet und analysiert. Um die dynamische Stabilität abzuschätzen, wurden Phonon-Berechnungen durchgeführt. In letzter Zeit wurden ionische und kovalente Systeme mit Simulated Annealing mit ab-initio Energieberechnungen in allen Schritten untersucht. In dieser Arbeit betrachteten wir CaC2 als Beispiel für ein gemischt kovalent-ionisches System. Experimentell waren vier verschiedene Modifikationen bekannt. Aus den globalen Optimierungen bei Normaldruck erhalten wir 10 verschiedene Strukturkandidaten für dieses System. Von diesen zeigen drei eine besonders niedrige Energie. Eine von ihnen ist die experimentell gefundene (CaC2-I)-Struktur, die zweite (CaC2-VI) hat einige Ähnlichkeiten mit der beobachteten (CaC2-III)-Struktur. Die dritte Struktur ist komplett neu (CaC2-V), und ist die mit der niedrigsten Energie aller berücksichtigten Strukturen. Ferner wird vorhergesagt, dass sich CaC2 unter hohem Druck in einem neuen Strukturtyp (CaC2-VII, analog zur CsCl-Struktur) stabilisiert. Diese vorhergesagte Modifikation wurde kürzlich in Hochdruckexperimenten am BaC2-System beobachtet. Die erfolgreiche Struktur-Vorhersage für das CaC2-System legte nahe, dass binäre Pernitrid-Verbindungen auch ein sehr interessantes System mit komplexen Multi-Minima-Energielandschaften sein könnten. In dieser Arbeit betrachten wir Pernitride MN2, wobei M Kationen mit unterschiedlichen maximalen Valenzen bezeichnet: II (Ca, Sr, Ba), III (La) und IV (Ti), von denen einige noch nicht synthetisiert wurden (LaN2 und TiN2). Experimentell kristallisieren CaN2 und SrN2 in einer tetragonalen Modifikation (CaC2-I), BaN2 im ThC2 Strukturtyp. Hierbei führten wir die Vorhersage der neuen Kristallstrukturen mit zwei Methoden durch: der globalen Suche, wie zuvor beschrieben, und einem einfachen Datenbankansatz. Im letzteren Ansatz verwendeten wir die bekannten AB2 Strukturtypen, die aus Datenbanken wie etwa der Inorganic Crystal Structure Database (ICSD) bekannt sind, ersetzten die Anionen und Kationen mit N2-Einheiten bzw. Metallatomen, und führten eine lokale Optimierung durch. Wir fanden die CaC2-I, ThC2, MgC2, und CaC2-V Modifikationen unter allen Pernitridsystemen als Kandidaten für stabile Modifikationen. Bei CaN2 sind die CaC2-I und MgC2 Strukturtypen stabile Modifikationen unter Standard- und Unterdruck. TiN2-I und CaC2-V sind m¨ogliche Modifikationen für das TiN2 System bei Normaldruck und bei hohem Druck. Im Fall von CaN2 und SrN2 sind die N2-Einheiten von oktaedrisch koordinierten Kationen umgeben, während bei BaN2 und LaN2 bei Standardbedingungen durch die Kationen ein verzerrter Oktaeder gebildet wird. Nur für das TiN2 System werden die N2-Hanteln von quadratischen Pyramiden aus Ti umgeben. All diese Pernitridmodifikationen sind metallischer Natur außer TiN2-I. Pernitridsysteme verfügen über eine negative Bindungsenergie in Bezug auf elementares Metall und N2, was darauf hindeutet, dass diese Systeme unter hohem Druck hergestellt werden könnten